Jounce bumpers are often mounted on a strut assembly, as shown in U.S. Pat. No. 5,487,535, where a jounce bumper surrounds a piston rod of a strut suspension. The jounce bumper prevents the cylinder of the strut assembly from heavily impacting the strut mounting assembly. Jounce bumpers are also commonly mounted in other locations, as shown in U.S. Pat. No. 5,725,203, where the jounce bumper is free standing to prevent a control arm of the suspension system from impacting with the vehicle frame.
Jounce bumpers can be mounted in a free state or with a rigid cup. Commonly assigned U.S. Pat. No. 6,158,726 discloses a jounce bumper with the use of a rigid cup that is designed to be attached to the vehicle frame. The rigid cup acts to attach the jounce bumper to the vehicle (or alternatively the strut) and limits the jounce bumper distortion, thereby increasing its spring rate. The force necessary to compress the jounce bumper increases as the jounce bumper is compressed and the jounce bumper absorbs energy as it is compressing. As the jounce bumper is compressed, the resistance to compression increases to the point where the jounce bumper acts as a solid, and transfers the remaining energy from the impact to the vehicle. The use of a rigid cup or another constraint limits the bulging of the bumper, thereby reducing the amount of travel needed to reach the point where the bumper becomes a solid. In general, when more energy must be removed, a larger bumper is used.
Microcellular urethane (MCU) bumpers are used in vehicle suspensions to absorb energy during jounce and to act as a supplemental spring as is shown in U.S. Pat. No. 5,467,970. One consideration with regard to the use of MCU bumpers is the ability to retain the MCU bumper which is subjected to both vertical and side-loaded pull-out forces.